This proposal will create an integrated software package for investigation of hormone concentration-time series by further development, extension, validation, and distribution of the data analysis algorithms and software created by our group over the last twenty years. These programs explore the aperiodic fluctuations that are typical for serum concentration profiles of many neuroendocrine and peripherally secreted hormones. Extensive experimental and theoretical work documents the physiological importance of these fluctuations that could be altered by pathophysiology, or could mediate key intra- and interspecies distinctions. However, the evolving demands of endocrine researchers cannot be adequately addressed by our current programs, which are based on outdated computer platforms, user interfaces, and lack extensive documentation. Accordingly, we propose to develop an integrated package of advanced data analysis algorithms, attendant software and documentation for multifaceted investigation of endocrine concentration-time series. The suite will encompass established and modem algorithms, as well as a contemporary user interface to facilitate the application by clinical investigators. In addition, the software and documentation will be freely accessible for research purposes. To meet these goals, we intend to upgrade our existing software to utilize a modern user interface in the framework of MS-Windows NT/2000/XP operating system (Aim 1). Inclusion of contemporary algorithms. (Aim 2) will expand the software capabilities and provide more precision, additional information, and increased user functionality. Special emphasis will be placed on improving the raw data preprocessing techniques (Aim 3), and on validation and testing of the new algorithms with simulated and experimental data (Aim 5). Extensive documentation will be created to ensure proper understanding and usage of the software and to facilitate future modifications by us and/or other investigators (Aim 4). The software and documentation will be available as we expand our World Wide Web presence (Aim 6). Improving and expanding our annual "Workshop on the Analysis of Hormone Pulsatility". (Aim 7) will further popularize the software package and supply essential feedback. This effort will provide the endocrine research community with contemporary, easy-to-use, computer- based tools for studying, individually or jointly, various characteristics of a single or multiple related hormone concentration-time series. We also envision potential applications in other non-endocrine research fields.